You can up your game with the one shot groups if you have the room. But it’s not necessary if it’s out of the intended use of the gun. For years, once I get a gun dialed, I will test it for weeks or even months. There has to be either a distance or a timeframe when the gun will finally let me down. I’ve never done it with a pellet gun but all my slug guns must pass the test. Or at the very least I will find out the guns limitations. Then go from there.
I start at 50 yards. After a week and a tiny little group appearing at 50, I move to 75 yards. After one shot a day or every other day and another little group, I move to 100. If things get a little weird once I’m out there at 100, 115 or 135 yards, I might move the target back in 10 yards at a time to see if I can pinpoint when the gun or me went off the rails. It’s a fun way to finalize a gun and there are not tons of slugs and cleaning regimens involved.
The skunk gun I mentioned is beyond 150 yards solid. But I have another one that I don’t sweat a true cold shot at 135. That’s where I kinda stopped my testing because I don’t have a need for a longer cold shot with that gun. Same with my .22. I’m currently and casually testing a .30. I’ve done plenty of shooting out to 200 yards but now it’s time to see how the gun behaves without foreplay. Lots of guns do great once you get their juices flowing but stink otherwise. They can go back to being a plinking pellet gun as far as I’m concerned.